In some cases, an ailment that a patient has may affect the quality of the patient's sleep. For example, chronic pain may cause a patient to have difficulty falling asleep, and may disturb the patient's sleep, e.g., cause the patient to wake. Further, chronic pain may cause the patient to have difficulty achieving deeper sleep states, such as the nonrapid eye movement (NREM) sleep state.
Other ailments that may negatively affect patient sleep quality include movement disorders, such as tremor, Parkinson's disease, multiple sclerosis, epilepsy, or spasticity. The uncontrolled movements associated with such movement disorders may cause a patient to have difficulty falling asleep, disturb the patient's sleep, or cause the patient to have difficulty achieving deeper sleep states. Psychological disorders, such as depression, mania, bipolar disorder, or obsessive-compulsive disorder, as well as sleep apnea, congestive heart failure, gastrointestinal disorders and incontinence may also similar affect the ability of a patient to sleep, or at least experience quality sleep. In the case of depression, a patient may “sleep” for long periods of the day, but the sleep is not restful, e.g., includes excessive disturbances and does not include deeper, more restful sleep states. In some cases, these ailments are treated via an implantable medical device (IMD), such as an implantable stimulator or drug delivery device. Movement disorders and psychological disorders are examples of neurological disorders.
Further, in some cases, poor sleep quality may increase the symptoms experienced by a patient due to an ailment. For example, poor sleep quality has been linked to increased pain symptoms in chronic pain patients, and may also result in increased movement disorder symptoms in movement disorder patients. Further, poor sleep quality may exacerbate many psychological disorders, such as depression. The link between poor sleep quality and increased symptoms is not limited to ailments that negatively impact sleep quality, such as those listed above. Nonetheless, the condition of a patient with such an ailment may progressively worsen when symptoms disturb sleep quality, which in turn increases the frequency and/or intensity of symptoms.